Bachelor of Science in Civil and Environmental Engineering

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Browsing Bachelor of Science in Civil and Environmental Engineering by Author "Bibian Kirabo"

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    Investigating the Use of Hydrated Lime and Rice Husk Ash in Stabilization of Silty Clays Soils Case Study: Nakivubo Primary School in Kampala Metropolitan
    (2024-04-16) Bibian Kirabo
    Silty clay soils are fine-grained soils widely distributed over the world and present quite a number of construction-related issues such as increased compressibility, decreased shear strength, and a propensity for shrinkage and swelling tendencies. This research focuses on stabilization of the silty clay soils using hydrated lime and rice husk ash to improve the properties of silty clay soils. Hydrated lime reacts with clay minerals to form calcium silicate hydrate (CSH), a cementitious compound which strengthens the soil and reduces its compressibility. Rice husk ash contains silica and alumina, which further contributes to pozzolanic reactions and enhances the soil's strength. The combination of these two stabilizers significantly improves compressive and shear strength, reduce shrinkage-swell potential, ensuring stable foundations and long-term durability making them more suitable for construction applications. Laboratory tests confirmed the soil's classification as A-7 (high plasticity) with a low CBR of 8%. Rice husk ash satisfied the pozzolanic material criteria. The optimal stabilization combination involved 4% hydrated lime and 8% rice husk ash, significantly reducing plasticity index and increasing CBR to 35%. This combination achieved the minimum UCS requirement of 0.5MPa for durability. The mechanism involves pozzolanic reactions between rice husk ash's silica and hydrated lime's calcium, leading to improved strength and reduced moisture sensitivity.